1. The Field of the Invention
The present invention relates to analog circuit design, and more specifically, to dual differential-input amplifiers and comparators having wide input range.
2. Background and Related Art
Analog circuits have revolutionized the way people work and play and have contributed enormously to the advancement of humankind. A key component of many analog circuit designs is the operational amplifier. An operational amplifier is a type of amplifier that when appropriately configured with external elements may perform mathematical operations. For example, an operational amplifier having it output coupled to an inverter causes the operational amplifier and inverter combination to act as a comparator in which the binary value at the output of the inverter is representative of which of the operational amplifier input terminals has a higher voltage.
In a standard differential-input operational amplifier, each of two differential input terminals is coupled to a control terminal of a single transistor (e.g., the gate terminal of a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), or the base terminal of a bipolar transistor). Dual differential-input operational amplifiers are useful in some applications as they have a tendency towards a wider input range. In dual differential-input operational amplifiers, each of two differential input terminals is coupled to a control terminal of two transistors. Wide input range is a desirable feature for many analog circuit applications as is know to those of ordinary skill in the art.
There are many conventional dual differential-input amplifier designs. Each design has its advantages and disadvantages. The desirability of the advantage and the acceptability of the disadvantage depend heavily upon the application. Additional alternatives provide a wider selection from which circuit designers may choose. Accordingly, what would be advantageous would be a new design for a dual differential-input operational amplifier.